Spinal implant system and methods of use

ABSTRACT

A bone fastener comprises a first member defining an implant cavity and a plurality of adjacent grooves. A first band is configured for disposal within the grooves. A second band is configured for disposal within the grooves. A second member is configured to penetrate tissue and includes a head engageable with the first band to provisionally connect the members. The second band is movable for disposal adjacent the first band to fix connection of the members. Implants, systems, instruments and methods are disclosed.

TECHNICAL FIELD

The present disclosure generally relates to medical devices for thetreatment of spinal disorders, and more particularly to a surgicalimplant system including a bone fastener and a related method.

BACKGROUND

Spinal pathologies and disorders such as scoliosis and other curvatureabnormalities, kyphosis, degenerative disc disease, disc herniation,osteoporosis, spondylolisthesis, stenosis, tumor, and fracture mayresult from factors including trauma, disease and degenerativeconditions caused by injury and aging. Spinal disorders typically resultin symptoms including deformity, pain, nerve damage, and partial orcomplete loss of mobility.

Non-surgical treatments, such as medication, rehabilitation and exercisecan be effective, however, may fail to relieve the symptoms associatedwith these disorders. Surgical treatment of these spinal disordersincludes correction, fusion, fixation, discectomy, laminectomy andimplantable prosthetics. As part of these surgical treatments, spinalconstructs such as vertebral rods are often used to provide stability toa treated region. Rods redirect stresses away from a damaged ordefective region while healing takes place to restore proper alignmentand generally support the vertebral members. During surgical treatment,one or more rods and bone fasteners can be delivered to a surgical site.The rods may be attached via the fasteners to the exterior of two ormore vertebral members. This disclosure describes an improvement overthese prior technologies.

SUMMARY

In one embodiment, a bone fastener is provided. The bone fastenercomprises a first member defining an implant cavity and a plurality ofadjacent grooves. A first band is configured for disposal within thegrooves. A second band is configured for disposal within the grooves. Asecond member is configured to penetrate tissue and includes a headengageable with the first band to provisionally connect the members. Thesecond band is movable for disposal adjacent the first band to fixconnection of the members. In some embodiments, implants, systems,instruments and methods are disclosed.

In one embodiment, the bone fastener comprises a first member thatdefines an implant cavity and a plurality of adjacent grooves. Thegrooves include a first portion and a second portion having a greaterdiameter than the first portion. A first band and a second band areconfigured for disposal within the grooves in an expanded configurationin the second portion and a contracted configuration in the firstportion. A second member is configured to penetrate tissue and includesa head engageable with the first band to connect the members. A part isengageable with the second band to fix the second band adjacent thefirst band. In some embodiments, the first band is configured fordisposal within the grooves in an expanded configuration while thesecond band is configured for disposal within the grooves in acontracted configuration. In some embodiments, the second band includesa free orientation that is expanded and the first band includes a freeorientation that is contracted so that it provides a tactile audibleindicia when moving the second member into the first member.

In one embodiment, the bone fastener comprises a first member thatdefines an implant cavity and a plurality of adjacent grooves. Thegrooves include a first groove, a second groove and a third groove. Thesecond groove has a greater diameter than the first groove and the thirdgroove. A first expandable band is configured for disposal within thegrooves. A second expandable band is configured for disposal within thegrooves. A second member is configured to penetrate tissue and includesa head engageable with the first band for translation from the firstgroove to the second groove to provisionally connect the members. A partis engageable with the second band for translation from the third grooveto the second groove such that the second band prevents the first bandfrom translating back into the second groove to fix connection of themembers. In some embodiments, the second band engages the first band fortranslation to the second groove and restricts any further translationof the first band to fix connection of first member to second member.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more readily apparent from thespecific description accompanied by the following drawings, in which:

FIG. 1 is a side cross section view of components of one embodiment of aspinal implant system in accordance with the principles of the presentdisclosure;

FIG. 2 is a break away view of the components shown in FIG. 1;

FIG. 3 is a side cross section view of the components shown in FIG. 1;

FIG. 4 is a break away view of the components shown in FIG. 1;

FIG. 5 is a break away view of the components shown in FIG. 1; and

FIG. 6 is a break away view of the components shown in FIG. 1.

DETAILED DESCRIPTION

The exemplary embodiments of a surgical system and related methods ofuse disclosed are discussed in terms of medical devices for thetreatment of musculoskeletal disorders and more particularly, in termsof a spinal implant system including a bone fastener. In one embodiment,the present spinal implant system includes an implant comprising a bonefastener, such as, for example, a pedicle bone screw. In someembodiments, the systems and methods of the present disclosure areemployed with a spinal joint fusion or fixation procedure, for example,with a cervical, thoracic, lumbar and/or sacral region of a spine.

In some embodiments, the present spinal implant system comprises amodular pedicle screw system including a double ring configuration. Insome embodiments, the present spinal implant system comprises amechanism to resist and/or prevent disengagement of a retainer of amodular screw system. In some embodiments, the present spinal implantsystem comprises a modular pedicle screw system including a screw shank,a receiver, a retainer and a compression insert. In some embodiments,the screw shank is inserted into the receiver and contacts the retainertranslating the retainer from a first chamber to a second chamber. Insome embodiments, the second chamber is oversized allowing for expansionof the retainer as the screw shank is translated further into thereceiver. In some embodiments, the spinal implant system comprises amodular pedicle screw system having an additional expansion memberconfigured to block the second chamber after the screw shank is engagedwith the receiver. In some embodiments, blocking of the second chamberresists and/or prevents the retainer from migrating back into the secondchamber and to resist and/or prevent disengagement of the components.

In some embodiments, the present spinal implant system comprises amodular assembly consisting of a receiver, expansion member, retainerand compression member. In some embodiments, the receiver includesfirst, second, and third chambers. In some embodiments, the firstchamber is sized to be a close fit to a retainer member and the secondchamber is oversized to allow expansion of the retainer. In someembodiments, the expansion of the retainer allows a screw shank to passthrough the retainer. In some embodiments, a second expansion member isnested in an undersized third chamber, which causes the expansion memberto collapse, such as, for example, by a reduction in diameter. Theexpansion member contains an outer groove, which mates with the receiverto prevent unintentional disengagement. In some embodiments, theexpansion member in the relaxed state is sized with a diameter similarto the second chamber. In some embodiments, the spinal implant systemincludes a compression member positioned above the expansion member.

In some embodiments, the present spinal implant system is employed witha method of attaching a tulip assembly with a screw shank including thesteps of translating the screw shank such that the retainer translatesinto the second chamber and expands then contracts to provisionallycapture the screw shank. In some embodiments, the method includes thestep of, once the screw shank is provisionally captured, the compressionmember being translated towards the expansion member forcing theexpansion member into the second chamber. In some embodiments, when theexpansion member is fully in the second chamber it is allowed to expand.As such, the expansion member allows for the compression member to passthrough its inner diameter in the expanded state. In some embodiments,the expansion member is sized to prevent the retainer member fromdisengaging from the first chamber. In some embodiments, the retainerpositioned in the first chamber resists and/or prevents the retainerfrom expanding and retains the screw shank in the tulip assembly.

In some embodiments, the spinal implant system comprises a modularsystem that includes a bone fastener including an array of members, suchas, for example, bone screw shafts that can be selectively coupled tomembers, such as, for example, receivers. In some embodiments, thespinal implant system comprises a selectively coupled bone fastener thatcan be assembled on a surgical table or in-situ. In some embodiments,the bone fastener is selectively coupled with a non-instrumentedassembly and/or manual assembly. In some embodiments, thenon-instrumented assembly comprises manually engaging a screw shaft witha head/receiver of the bone fastener. In some embodiments, thenon-instrumented assembly comprises manually engaging the screw shaft ina pop-on engagement with the head/receiver of the bone fastener. In someembodiments, a force required to manually engage a screw shaft with ahead/receiver of the bone fastener in a non-instrumented assembly is ina range of 2 to 50 N. In some embodiments, a force required to manuallyengage a screw shaft with a head/receiver of the bone fastener in anon-instrumented assembly is in a range of 5 to 10 N. In someembodiments, this configuration provides manually engageable componentsof a bone fastener that are assembled without instrumentation, andsubsequent to assembly, the assembled components have a selectedpull-out strength and/or can be pulled apart, removed and/or separatedwith a minimum required force.

In some embodiments, the bone fastener is configured for assemblywithout the use of an instrument, such as, for example, a practitioner,surgeon and/or medical staff utilizes their hands for assembly. In someembodiments, the system requires minimal force to attach an implantreceiver and a screw shaft assembly in-situ thereby reducing a pre-loadon the vertebrae, such as, for, example, the pedicle. In someembodiments, the bone fastener includes an expandable ring.

In some embodiments, the present disclosure may be employed to treatspinal disorders such as, for example, degenerative disc disease, discherniation, osteoporosis, spondylolisthesis, stenosis, scoliosis andother curvature abnormalities, kyphosis, tumor and fractures. In someembodiments, the present disclosure may be employed with other ostealand bone related applications, including those associated withdiagnostics and therapeutics. In some embodiments, the disclosed spinalimplant system may be alternatively employed in a surgical treatmentwith a patient in a prone or supine position, and/or employ varioussurgical approaches to the spine, including anterior, posterior,posterior mid-line, lateral, postero-lateral, and/or antero-lateralapproaches, and in other body regions. The present disclosure may alsobe alternatively employed with procedures for treating the lumbar,cervical, thoracic, sacral and pelvic regions of a spinal column. Thespinal implant system of the present disclosure may also be used onanimals, bone models and other non-living substrates, such as, forexample, in training, testing and demonstration.

The present disclosure may be understood more readily by reference tothe following detailed description of the embodiments taken inconnection with the accompanying drawing figures, which form a part ofthis disclosure. It is to be understood that this application is notlimited to the specific devices, methods, conditions or parametersdescribed and/or shown herein, and that the terminology used herein isfor the purpose of describing particular embodiments by way of exampleonly and is not intended to be limiting. In some embodiments, as used inthe specification and including the appended claims, the singular forms“a,” “an,” and “the” include the plural, and reference to a particularnumerical value includes at least that particular value, unless thecontext clearly dictates otherwise. Ranges may be expressed herein asfrom “about” or “approximately” one particular value and/or to “about”or “approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment. It isalso understood that all spatial references, such as, for example,horizontal, vertical, top, upper, lower, bottom, left and right, are forillustrative purposes only and can be varied within the scope of thedisclosure. For example, the references “upper” and “lower” are relativeand used only in the context to the other, and are not necessarily“superior” and “inferior”.

As used in the specification and including the appended claims,“treating” or “treatment” of a disease or condition refers to performinga procedure that may include administering one or more drugs to apatient (human, normal or otherwise or other mammal), employingimplantable devices, and/or employing instruments that treat thedisease, such as, for example, microdiscectomy instruments used toremove portions bulging or herniated discs and/or bone spurs, in aneffort to alleviate signs or symptoms of the disease or condition.Alleviation can occur prior to signs or symptoms of the disease orcondition appearing, as well as after their appearance. Thus, treatingor treatment includes preventing or prevention of disease or undesirablecondition (e.g., preventing the disease from occurring in a patient, whomay be predisposed to the disease but has not yet been diagnosed ashaving it). In addition, treating or treatment does not require completealleviation of signs or symptoms, does not require a cure, andspecifically includes procedures that have only a marginal effect on thepatient. Treatment can include inhibiting the disease, e.g., arrestingits development, or relieving the disease, e.g., causing regression ofthe disease. For example, treatment can include reducing acute orchronic inflammation; alleviating pain and mitigating and inducingre-growth of new ligament, bone and other tissues; as an adjunct insurgery; and/or any repair procedure. Also, as used in the specificationand including the appended claims, the term “tissue” includes softtissue, ligaments, tendons, cartilage and/or bone unless specificallyreferred to otherwise.

The following discussion includes a description of a surgical systemincluding a bone fastener, related components and methods of employingthe surgical system in accordance with the principles of the presentdisclosure. Alternate embodiments are also disclosed. Reference is madein detail to the exemplary embodiments of the present disclosure, whichare illustrated in the accompanying figures. Turning to FIGS. 1-6, thereare illustrated components of a spinal implant system 10.

The components of spinal implant system 10 can be fabricated frombiologically acceptable materials suitable for medical applications,including metals, synthetic polymers, ceramics and bone material and/ortheir composites. For example, the components of spinal implant system10, individually or collectively, can be fabricated from materials suchas stainless steel alloys, commercially pure titanium, titanium alloys,Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys,superelastic metallic alloys (e.g., Nitinol, super elasto-plasticmetals, such as GUM METAL®), ceramics and composites thereof such ascalcium phosphate (e.g., SKELITE™), thermoplastics such aspolyaryletherketone (PAEK) including polyetheretherketone (PEEK),polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEKcomposites, PEEK-BaSO₄ polymeric rubbers, polyethylene terephthalate(PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers,polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigidmaterials, elastomers, rubbers, thermoplastic elastomers, thermosetelastomers, elastomeric composites, rigid polymers includingpolyphenylene, polyimide, polyimide, polyetherimide, polyethylene,epoxy, bone material including autograft, allograft, xenograft ortransgenic cortical and/or corticocancellous bone, and tissue growth ordifferentiation factors, partially resorbable materials, such as, forexample, composites of metals and calcium-based ceramics, composites ofPEEK and calcium based ceramics, composites of PEEK with resorbablepolymers, totally resorbable materials, such as, for example, calciumbased ceramics such as calcium phosphate, tri-calcium phosphate (TCP),hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymerssuch as polyaetide, polyglycolide, polytyrosine carbonate,polycaroplaetohe and their combinations.

Various components of spinal implant system 10 may have materialcomposites, including the above materials, to achieve various desiredcharacteristics such as strength, rigidity, elasticity, compliance,biomechanical performance, durability and radiolucency or imagingpreference. The components of spinal implant system 10, individually orcollectively, may also be fabricated from a heterogeneous material suchas a combination of two or more of the above-described materials. Thecomponents of spinal implant system 10 may be monolithically formed,integrally connected or include fastening elements and/or instruments,as described herein.

Spinal implant system 10 includes a spinal implant, such as, forexample, a bone fastener 180. Bone fastener 180 comprises a member, suchas, for example, a screw shaft assembly 12 and a member, such as, forexample a head assembly 13. Head assembly 13 includes a band, such as,for example, a retaining ring 36 configured for provisional capture ofscrew shaft assembly 12 and/or fixed connection of the components ofbone fastener 180, as described herein. Head assembly 13 includes aband, such as, for example, a ring 44 configured for disposal in acontracted orientation and an expanded interference orientation adjacentto ring 36 to facilitate fixed connection of the components of bonefastener 180. In some embodiments, screw shaft assembly 12 and headassembly 13 are assembled in situ or prior to implant to form bonefastener 180, as described herein.

Head assembly 13 includes a receiver 14. Receiver 14 extends along anddefines an axis X1. Receiver 14 includes a pair of spaced apart arms 16,18 that define an implant cavity 20 therebetween configured for disposalof a component of a spinal construct, such as, for example, a spinal rod(not shown).

Arms 16, 18 each extend parallel to axis X1. In some embodiments, arm 16and/or arm 18 may be disposed at alternate orientations, relative toaxis X1, such as, for example, transverse, perpendicular and/or otherangular orientations such as acute or obtuse, coaxial and/or may beoffset or staggered. Arms 16, 18 each include an arcuate outer surfaceextending between a pair of side surfaces. At least one of the outersurfaces and the side surfaces of arms 16, 18 have at least one recessor cavity therein configured to receive an insertion tool, compressioninstrument and/or instruments for inserting and tensioning bone fastener180. In some embodiments, arms 16, 18 are connected at proximal anddistal ends thereof such that receiver 14 defines a closed spinal rodslot. In some embodiments, a spinal rod may be monolithically formedwith receiver 14 or pre-assembled with receiver 14.

Cavity 20 is substantially U-shaped. In some embodiments, all or only aportion of cavity 20 may have alternate cross section configurations,such as, for example, closed, V-shaped, W-shaped, oval, oblongtriangular, square, polygonal, irregular, uniform, non-uniform, offset,staggered, and/or tapered. Receiver 14 includes an inner surface 22. Aportion of surface 22 includes a thread form 24 located adjacent arm 16and a thread form 26 located adjacent arm 18. Thread forms 24, 26 areeach configured for engagement with a coupling member, such as, forexample, a setscrew (not shown), to retain the spinal rod within cavity20. In some embodiments, surface 22 may be disposed with the couplingmember in alternate fixation configurations, such as, for example,friction fit, pressure fit, locking protrusion/recess, locking keywayand/or adhesive. In some embodiments, all or only a portion of surface22 may have alternate surface configurations to enhance engagement withthe spinal rod and/or the setscrew, such as, for example, rough,arcuate, undulating, mesh, porous, semi-porous, dimpled and/or textured.In some embodiments, receiver 14 may include alternate configurations,such as, for example, closed, open and/or side access. In someembodiments, screw shaft assembly 12 is manually engaged with headassembly 13 in a non-instrumented assembly, as described herein, suchthat removal of head assembly 13 from screw shaft assembly 12 canwithstand a clamp force applied from the coupling member.

Receiver 14 includes portion 28, as shown in FIG. 2. Portion 28 includesa surface 30. Surface 30 defines a cavity, such as, for example, agroove 34. Groove 34 is configured for disposal of ring 36. In someembodiments, groove 34 extends about all or a portion of surface 30.Groove 34 includes a diameter D1. Ring 36 includes a circumference thatdefines an opening, such as, for example, a gap. In some embodiments,the gap is sized such that the gap has a thickness that is less than theheight and the width. In some embodiments, the gap is sized to allowring 36 to pass though a bottom of receiver 14 by contractingcircumferentially.

Portion 28 includes a surface 40, as shown in FIG. 2. Surface 40 definesa cavity, such as, for example, a groove 42. Groove 42 is configured fordisposal of ring 44. Ring 44 includes a surface 46 that defines an outergroove 48 configured for engagement with a surface of groove 42, asdescribed herein. Ring 44 includes a circumference that extends betweenends of ring 44. In some embodiments, the ends define an opening, suchas, for example, a gap. In some embodiments, the gap is sized such thatthe gap has a thickness that is less than the height and the width. Insome embodiments, the gap is sized to allow ring 44 to engage surface 40by contracting circumferentially.

Groove 42 includes a projection 50. Projection 50 is configured forengagement with surface 46 of outer groove 48. Projection 50 retainsring 44 within groove 42. Projection 50 is configured to resist and/orprevent disengagement of ring 44 from groove 42. Ring 44 isdisengageable from groove 42 upon engagement with crown 80, which causessurface 46 to disengage from projection 50 and drives ring 44 fromgroove 42, as described herein. Groove 42 includes a diameter D2. Insome embodiments, diameter D1 is equal to diameter D2, as shown in FIG.2. In some embodiments, diameter D1 and diameter D2 are different. Insome embodiments, surface 40 retains ring 44 within groove 42 and groove42 does not include projection 50.

Receiver 14 includes a portion 60, as shown in FIG. 2. Portion 60includes a surface 62. Surface 62 defines a cavity, such as, forexample, a groove 64 configured for disposal of ring 36 and/or ring 44.In some embodiments, groove 64 extends about all or a portion of surface40. Groove 64 includes a circumferential channel 66 that accommodatesexpansion of ring 36 and/or ring 44, as described herein. Groove 64includes a diameter D3. Diameter D3 is greater than diameter D1 and/ordiameter D2. Diameter D3 is sized to allow for expansion of ring 36and/or ring 44 therein. Grooves 34, 42, 64 are disposed in a serialorientation along axis X1, as shown in FIG. 2. In some embodiments,grooves 34, 42, 64 are disposed in spaced apart relation.

A surface 68 is disposed between groove 64 and groove 34. Surface 68 isdisposed at an angle relative to axis X1 to define a ramp 69. Ramp 69 isselectively inclined to facilitate translation of ring 36 between groove34 and groove 64, as described herein. In one example, ring 36 isengaged with screw shaft assembly 12 for translation such that ring 36slides along ramp 69, which directs and/or guides ring 36 from groove 34into groove 64, and expands into a provisional capture orientation withscrew shaft assembly 12. In another example, ring 36 is engaged withring 44 for translation such that ring 36 slides along ramp 69, whichdirects and/or guides ring 36 from groove 64 into groove 34, andcontracts for fixed connection of the components of bone fastener 180including permanent capture of head assembly 13 and screw shaft assembly12. In some embodiments, surface 68 is oriented substantiallyperpendicular to axis X1.

Ring 36 is resiliently biased to a contracted and/or capture orientationwithin groove 34, as shown in FIG. 3, and expandable to an expandedorientation within groove 64, as shown in FIGS. 4 and 5, for provisionalcapture of screw shaft assembly 12 with head assembly 13, as describedherein. Ring 36 is expandable from the contracted and/or captureorientation to the expanded orientation for assembly of screw shaftassembly 12 with head assembly 13, as shown and described for examplewith regard to FIGS. 3-6.

Ring 44 is disposable in a contracted orientation within groove 42, asshown in FIGS. 3-5, and resiliently biased to an expanded interferenceorientation within groove 64, as shown in FIG. 6. In the interferenceorientation, ring 44 is disposed in channel 66 and adjacent to ring 36for abutting and/or contacting engagement therewith to resist and/orprevent translation of ring 36 from groove 34 into groove 64, and fixedconnection of the components of bone fastener 180 including permanentcapture of head assembly 13 and screw shaft assembly 12, as describedherein.

Receiver 14 includes a surface 70. Surface 70 defines a slot 72. Slot 72is configured for disposal of a part, such as, for example a crown 80.In some embodiments, all or only a portion of surface 70 may havealternate surface configurations, such as, for example, rough, arcuate,undulating, mesh, porous, semi-porous, dimpled and/or textured.

Crown 80 is configured for disposal within cavity 20 and slot 72. Crown80 includes a wall 82 having an end surface 84 and an end surface 86.Surface 84 is configured to define at least a portion 88 of cavity 20.Portion 88 is defined by an outer surface 90 that defines a curvedportion of crown 80 configured for engagement with a spinal implant,such as, for example, a spinal rod. Surface 84 includes acircumferential flange 92. Receiver 14 includes an undercut surface thatdefines a groove 94. Flange 92 is configured for disposal with groove94, as shown in FIG. 3. Engagement of flange 92 with the undercutsurface that defines groove 94 retains crown 80 with receiver 14 in afirst orientation adjacent ring 44 when ring 44 is disposed in groove42. Translation of crown 80, in a direction shown by arrow C anddescribed herein with regard to FIGS. 5 and 6, into a second orientationmoves ring 44 from groove 42. In some embodiments, all or only a portionof surface 90 may have alternate cross section configurations, such as,for example, oval, oblong triangular, square, polygonal, irregular,uniform, non-uniform, offset, staggered, and/or tapered. In someembodiments, a part, as described herein, may include a crown, a sleeveand/or other component of head assembly 13.

Crown 80 is configured for translation within slot 72 along surface 70.Translation of crown 80 within slot 72 causes surface 86 to engage ring44. Surface 86 is disposed adjacent ring 44 such that axial translationof crown 80 causes crown 80 to displace ring 44 from groove 42. Ring 44is disengageable from groove 42 upon engagement with crown 80, whichcauses surface 46 to disengage from projection 50 and drives ring 44from groove 42. As such, ring 44 is movable between the contractedorientation and the expanded interference orientation in groove 64, asdescribed herein, to prevent migration of ring 36 from groove 34 intogroove 64 for fixed connection of the components of bone fastener 180.Surface 86 is positioned with ring 44 to resist and/or preventdisplacement of ring 44 from channel 66.

Screw shaft assembly 12 includes shaft 181 and head 182. Shaft 181 isconfigured to penetrate tissue, such as, for example, vertebral tissue.In some embodiments, shaft 181 includes an outer surface having anexternal thread form. In some embodiments, the external thread form mayinclude a single thread turn or a plurality of discrete threads. Head182 includes a tool engaging portion 184 configured to engage a surgicaltool or instrument, as described herein. In some embodiments, portion184 includes a hexagonal cross-section. In some embodiments, portion 184may have alternative cross-sections, such as, for example, rectangular,polygonal, hexalobe, oval, or irregular. Head 182 includes a surface 186that defines a plurality of ridges 188 to improve purchase of head 182with crown 80. In some embodiments, head 182 includes an outer surface190 having planar surfaces or flats and/or arcuate surfaces.

In some embodiments, receiver 14 may be disposed with head 182 inalternate fixation configurations, such as, for example, friction fit,pressure fit, locking protrusion/recess, locking keyway and/or adhesive.In some embodiments, receiver 14 is configured for rotation relative tohead 182 for multi-axial movement. In some embodiments, receiver 14 isconfigured for rotation in range of 360 degrees relative to head 182 tofacilitate positioning of shaft 181 with tissue. In some embodiments,receiver 14 is configured for selective rotation in range of 360 degreesrelative to and about head 182 such that shaft 181 is selectivelyaligned for rotation in a plane relative to receiver 14. In someembodiments, receiver 14 may be disposed with head 182 in a uni-axialconfiguration or a sagittally adjustable configuration.

In some embodiments, screw shaft assembly 12 is manually engageable withhead assembly 13 in a non-instrumented assembly, as described herein. Insome embodiments, manual engagement and/or non-instrumented assembly ofhead assembly 13 and screw shaft assembly 12 includes coupling withoutuse of separate and/or independent instrumentation engaged with screwshaft assembly 12 components to effect assembly. In some embodiments,manual engagement and/or non-instrumented assembly includes apractitioner, surgeon and/or medical staff grasping head assembly 13 andscrew shaft assembly 12 and forcibly assembling the components. In someembodiments, manual engagement and/or non-instrumented assembly includesa practitioner, surgeon and/or medical staff grasping head assembly 13and screw shaft assembly 12 and forcibly snap fitting the componentstogether, as described herein. In some embodiments, manual engagementand/or non-instrumented assembly includes a practitioner, surgeon and/ormedical staff grasping head assembly 13 and screw shaft assembly 12 andforcibly pop fitting the components together and/or pop fitting headassembly 13 onto screw shaft assembly 12, as described herein. In someembodiments, a force in a range of 2-50 N is required to manually engagehead assembly 13 and screw shaft assembly 12 and forcibly assemble thecomponents. For example, a force in a range of 2-50 N is required tosnap fit and/or pop fit assemble head assembly 13 and screw shaftassembly 12. In some embodiments, a force in a range of 5-10 N isrequired to manually engage head assembly 13 and screw shaft assembly 12and forcibly assemble the components. For example, a force in a range of5-10 N is required to snap fit and/or pop fit assemble head assembly 13and screw shaft assembly 12. In some embodiments, this configurationprovides manually engageable components that are assembled withoutinstrumentation, and subsequent to assembly, the assembled componentshave a selected pull-out strength and/or can be pulled apart, removedand/or separated with a minimum required force.

In some embodiments, spinal implant system 10 comprises a spinal implantkit, as described herein, which includes a plurality of screw shaftassemblies 12 and/or head assemblies 13. Screw shaft assembly 12 and/orhead assembly is configured for selection such that the components ofbone fastener 180 are interchangeable.

In assembly, operation and use, spinal implant system 10, similar to thesystems and methods described herein, includes a screw shaft assembly 12for connection with a head assembly 13, and is employed with a surgicalprocedure for treatment of a spinal disorder affecting a section of aspine of a patient, as discussed herein. Spinal implant system 10 isemployed with a surgical procedure for treatment of a condition orinjury of an affected section of the spine.

In some embodiments, a screw shaft assembly 12 is selected from a kit ofa plurality of screw shaft assemblies 12 for interchangeable connectionwith head assembly 13 to comprise a bone fastener 180 having a selectedmovement, similar to those described herein. In some embodiments, thekit of screw shaft assemblies 12 includes a variety of screw shaftassemblies having different movement configurations when assembled withan interchangeable head assembly 13, such as, for example, multi-axialmovement, sagittal angulation movement, fixed axis movement, mono-axialmovement and/or uni-planar movement.

In some embodiments, head assembly 13 includes receiver 14 assembledwith crown 80, ring 44 and ring 36, as described herein. In someembodiments, ring 36 is initially disposed with groove 34 in acontracted orientation and ring 44 is initially disposed with groove 42in a contracted orientation, as shown in FIG. 3.

Screw shaft assembly 12 is manually engageable, as described herein,with head assembly 13, as shown in FIGS. 3-6. Head assembly 13 isassembled with screw shaft assembly 12 by translating receiver 14, in adirection shown by arrow A in FIG. 3. Engagement of head 182 withreceiver 14 causes ring 36 to translate, in a direction shown by arrow Bin FIG. 4, such that ring 36 is positionable and allowed to expand intogroove 64 to an expanded orientation, as described herein. Diameter D3of groove 64 is larger than diameter D1 of groove 34 to allow ring 36 toexpand into channel 66. Engagement of head 182 with an inner surface ofring 36 causes ring 36 to expand and slide along ramp 69 into channel66. As head 182 translates further into receiver 14, ring 36 passes overhead 182 and resiliently contracts about head 182 within channel 66 toprovisionally capture screw shaft assembly 12, as shown in FIG. 5.

Crown 80 is manipulated, for example, via engagement by a surgicalinstrument to translate crown 80, in a direction shown by arrow C inFIG. 5. Surface 86 engages ring 44 such that surface 46 disengages fromprojection 50 and ring 44 is displaced from groove 42, as shown in FIG.6. Ring 44 translates and engages ring 36 driving ring 36 from groove 64into groove 34. Ring 36 axially translates along receiver 14 and/orslides along ramp 69 into groove 34. Ring 44 translates into groove 64and resiliently expands into channel 66 to an expanded, interferenceorientation, as described herein. Ring 44 is oriented for abuttingand/or contacting engagement with ring 36 to resist and/or preventtranslation of ring 36 from groove 34 into groove 64, and fixedconnection of the components of bone fastener 180 including permanentcapture of head assembly 13 and screw shaft assembly 12 in a selectedmovement configuration, for example, in a multi-axial movementconfiguration. Surface 86 is positioned with ring 44 to resist and/orprevent displacement of ring 44 from channel 66.

In use, for treatment of a spinal disorder, bone fastener 180 includingassembled screw shaft assembly 12 and head assembly 13 can be threadedand engaged with tissue. In some embodiments, bone fastener 180 isdisposed adjacent vertebrae at a surgical site and is manipulated todrive, torque, insert or otherwise connect shaft 181 with vertebrae inconnection with a surgical procedure, as described herein.

In some embodiments, spinal implant system 10 includes an agent, whichmay be disposed, packed, coated or layered within, on or about thecomponents and/or surfaces of spinal implant system 10. In someembodiments, the agent may include bone growth promoting material, suchas, for example, bone graft to enhance fixation of the fixation elementswith vertebrae. In some embodiments, the agent may be HA coating. Insome embodiments, the agent may include one or a plurality oftherapeutic agents and/or pharmacological agents for release, includingsustained release, to treat, for example, pain, inflammation anddegeneration.

In some embodiments, the use of microsurgical and image guidedtechnologies may be employed to access, view and repair spinaldeterioration or damage, with the aid of spinal implant system 10. Thecomponents of spinal implant system 10 can be made of radiolucentmaterials such as polymers. Radiomarkers may be included foridentification under x-ray, fluoroscopy, CT or other imaging techniques.

In some embodiments, spinal implant system 10 can include one or aplurality of bone fasteners 180 such as those described herein and/orfixation elements, which may be employed with a single vertebral levelor a plurality of vertebral levels. In some embodiments, bone fasteners180 may be engaged with vertebrae in various orientations, such as, forexample, series, parallel, offset, staggered and/or alternate vertebrallevels. In some embodiments, bone fasteners 180 may be configured asmulti-axial screws, sagittal angulation screws, pedicle screws,mono-axial screws, uni-planar screws, fixed screws, anchors, tissuepenetrating screws, conventional screws, expanding screws. In someembodiments, bone fasteners 180 may be employed with wedges, anchors,buttons, clips, snaps, friction fittings, compressive fittings,expanding rivets, staples, nails, adhesives, posts, connectors, fixationplates and/or post.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplification of thevarious embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

What is claimed is:
 1. A bone fastener comprising: a first memberdefining an implant cavity and a plurality of adjacent grooves; a firstband configured for disposal within the grooves; a second bandconfigured for disposal within the grooves; and a second memberconfigured to penetrate tissue and including a head engageable with thefirst band to provisionally connect the members, the second band beingmovable for disposal adjacent the first band to fix connection of themembers.
 2. A bone fastener as recited in claim 1, further comprising apart engageable with the second band to dispose the second band adjacentthe first band to fix connection of the members.
 3. A bone fastener asrecited in claim 1, wherein the grooves include a first groove, a secondgroove and a third groove that are circumferentially disposed with aninner surface of the first member and along a longitudinal axis thereof.4. A bone fastener as recited in claim 3, wherein the first memberincludes a ramp surface disposed between the second groove and the firstgroove.
 5. A bone fastener as recited in claim 3, wherein the secondgroove has a larger diameter relative to the first groove and the thirdgroove.
 6. A bone fastener as recited in claim 3, wherein the first bandis contractible in the first groove and the second band is contractiblein the third groove, and the second groove is configured for expansionof the first band or the second band.
 7. A bone fastener as recited inclaim 1, wherein the grooves are disposed in a serial orientation alonga longitudinal axis of the first member.
 8. A bone fastener as recitedin claim 1, wherein at least one of the grooves includes a projectionengageable with a band.
 9. A bone fastener as recited in claim 1,wherein at least one of the grooves includes a circumferentialprojection engageable with a recess of a band.
 10. A bone fastener asrecited in claim 1, wherein the head is manually engageable with thefirst band to connect the members in a non-instrumented assembly.
 11. Abone fastener as recited in claim 1, further comprising a crown disposedwithin the implant cavity and having a distal face engageable with thesecond band.
 12. A bone fastener as recited in claim 1, wherein thefirst band is expandable between a provisional capture orientation andan expanded orientation, and the second band is expandable between acontracted orientation and an interference orientation to fix connectionof the members.
 13. A bone fastener as recited in claim 1, wherein atleast one of the bands is a circumferential ring that defines a gap. 14.A bone fastener comprising: a first member defining an implant cavityand a plurality of adjacent grooves including a first portion and asecond portion having a greater diameter than the first portion; a firstband and a second band configured for disposal within the grooves in anexpanded configuration in the second portion and a contractedconfiguration in the first portion; a second member configured topenetrate tissue and including a head engageable with the first band toconnect the members; and a part engageable with the second band to fixthe second band adjacent the first band.
 15. A bone fastener as recitedin claim 14, wherein the first portion includes a first groove and athird groove that are circumferentially disposed with an inner surfaceof the first member, and the second portion includes a second groovedisposed between the first groove and the third groove.
 16. A bonefastener as recited in claim 14, wherein the grooves are disposed in aserial orientation along a longitudinal axis of the first member.
 17. Abone fastener as recited in claim 14, wherein at least one of thegrooves includes a projection engageable with a band.
 18. A bonefastener as recited in claim 14, wherein the part includes a crowndisposed within the implant cavity and having a distal face engageablewith the second band.
 19. A bone fastener as recited in claim 14,wherein the first band is expandable between a provisional captureorientation and an expanded orientation, and the second band isexpandable between a contracted orientation and an interferenceorientation to fix connection of the members.
 20. A bone fastenercomprising: a first member defining an implant cavity and a plurality ofadjacent grooves including a first groove, a second groove and a thirdgroove, the second groove having a greater diameter than the firstgroove and the third groove; a first expandable band configured fordisposal within the grooves; a second expandable band configured fordisposal within the grooves; a second member configured to penetratetissue and including a head engageable with the first band fortranslation from the first groove to the second groove to provisionallyconnect the members; and a part is engageable with the second band fortranslation from the third groove to the second groove such that thesecond band prevents the first band from translating back into thesecond groove to fix connection of the members.